Electrically variable transmission having two or three planetary gear sets with two or three fixed interconnections

Abstract

The electrically variable transmission family of the present invention provides low-content, low-cost electrically variable transmission mechanisms including two or three differential gear sets, a battery, two electric machines serving interchangeably as motors or generators, and four or five selectable torque-transfer devices. The selectable torque transfer devices are engaged singly or in combinations of two or three to yield an EVT with a continuously variable range of speeds (including reverse) and four mechanically fixed forward speed ratios. The torque transfer devices and the first and second motor/generators are operable to provide five operating modes in the electrically variable transmission, including battery reverse mode, EVT reverse mode, reverse and forward launch modes, continuously variable transmission range mode, and fixed ratio mode.

1. An electrically variable transmission comprising:
 an input member to receive power from an engine; 
 an output member; 
 first and second motor/generators; 
 first, second and third differential gear sets each having first, second and third members; 
 said input member being continuously connected or selectively connected with a member of said gear sets, and said output member being continuously connected with another member of said gear sets; 
 a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; 
 a second interconnecting member continuously connecting said second member of said first gear set with said second member of said second gear set; 
 a third interconnecting member continuously connecting said first member of said third gear set with said second or third member of said second gear set or with a stationary member; 
 said first motor/generator being continuously or selectively connected with a member of said first or second gear set; 
 said second motor/generator being continuously connected with a member of said second or third gear set which is different from said member connected with said first motor/generator; 
 a first torque transfer device selectively connecting said input member or a member of said third gear set with a member of said first or second gear set; 
 a second torque transfer device selectively connecting said input member or a member of said third gear set with a member of said first, second or third gear set, this member being different from the one connected to said first torque transfer device; 
 a third torque transfer device selectively connecting a member of the first, second or third gear set with said stationary member or with said input member; 
 a fourth torque transfer device connected in parallel with said first or second motor/generator for selectively braking rotation thereof; 
 a fifth torque transfer device connected in parallel with the other of said first or second motor/generator for selectively braking rotation thereof; 
 wherein said first, second, third, fourth and fifth torque transfer devices are selectively engageable singly or in combinations of two or three to provide an electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios. 
 
     
     
       2. The electrically variable transmission of  claim 1 , wherein said first, second and third differential gear sets are planetary gear sets, each including a ring gear, a sun gear and a carrier. 
     
     
       3. The electrically variable transmission of  claim 2 , wherein carriers of each of said planetary gear sets are single-pinion carriers. 
     
     
       4. The electrically variable transmission of  claim 2 , wherein at least one carrier of said planetary gear sets is a double-pinion carrier. 
     
     
       5. The electrically variable transmission of  claim 1 , wherein said first motor/generator is continuously connected to a member of the first or second gear set. 
     
     
       6. The electrically variable transmission of  claim 1 , where said first motor/generator is selectively alternately connectable with two of said members of said first or second gear set through a dog clutch. 
     
     
       7. An electrically variable transmission comprising:
 an input member to receive power from an engine; 
 an output member; 
 first and second motor/generators; 
 first, second and third planetary gear sets each having first, second and third members; 
 said input member being continuously connected or selectively connected with a member of said gear sets, and said output member being continuously connected with another member of said gear sets; 
 a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; 
 a second interconnecting member continuously connecting said second member of said first gear set with said second member of said second gear set; 
 a third interconnecting member continuously connecting said first member of said third gear set with said second or third member of said second gear set or with a stationary member; 
 said first motor/generator being continuously or selectively connected with a member of said first or second gear set; 
 said second motor/generator being continuously connected with a member of said second or third gear set which is different from said member connected with said first motor/generator; and 
 first, second, third, fourth and fifth torque transfer devices which are engagable to selectively connect said members of said gear sets with other members of said gear sets, said input member, or with said stationary member, to provide an electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios; 
 wherein said first torque transfer device selectively connects said input member or a member of said third planetary gear set with a member of said first or second gear set, and said second torque transfer device selectively connects said input member or a member of said third planetary gear set with another member of said first, second, or third gear set; and 
 wherein one of said fourth and fifth torque transfer devices is implemented as a motor brake connected in parallel with one of said first and second motor/generators for use in establishing said fixed ratios, and the other of said fourth and fifth torque transfer devices is implemented as a motor brake connected in parallel with the other of said first and second motor/generators for selective braking thereof. 
 
     
     
       8. The electrically variable transmission of  claim 7 , wherein each of said planetary gear sets includes a ring gear, a sun gear and a carrier. 
     
     
       9. The electrically variable transmission of  claim 8 , wherein carriers of each of said planetary gear sets are single-pinion carriers. 
     
     
       10. The electrically variable transmission of  claim 8 , wherein at least one carrier of said planetary gear sets is a double-pinion carrier. 
     
     
       11. The electrically variable transmission of  claim 7 , wherein said third torque transfer device selectively connects a member of said first, second or third planetary gear set with a stationary member or with said input member. 
     
     
       12. An electrically variable transmission comprising:
 an input member to receive power from an engine; 
 an output member; 
 first and second motor/generators; 
 first and second differential gear sets each having first, second and third members; 
 said input member being continuously or selectively connected with a member of said gear sets, and said output member being continuously connected with another member of said gear sets; 
 a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; 
 a second interconnecting member continuously connecting said second member of said first gear set with said second member of said second gear set; 
 said first motor/generator being continuously or selectively connected with a member of said first or second gear set; 
 said second motor/generator being continuously connected with a member of said first or second gear set which is different from said member connected with said first motor/generator; 
 a first torque transfer device selectively connecting said input member or a member of said first gear set with a member of said first or second gear set; 
 a second torque transfer device selectively connecting said input member or a member of said first gear set with another member of said first or second gear set; 
 a third torque transfer device selectively connecting a member of said first or second gear set with a stationary member or with the input member; 
 a fourth torque transfer device connected in parallel with said first or second motor/generator for braking rotation thereof; 
 a fifth torque transfer device connected in parallel with the other of said first or second motor/generator for braking rotation thereof; 
 wherein said first, second, third, fourth and fifth torque transfer devices are selectively engageable to provide an electrically variable transmission with a continuously variable range of speed ratios and four forward speed ratios. 
 
     
     
       13. The electrically variable transmission of  claim 12 , wherein said first motor/generator is continuously connected to a member of said first gear set. 
     
     
       14. The electrically variable transmission of  claim 12 , further comprising a third gear set, and wherein said first motor/generator is selectively alternately connectable with two of said members of said second gear set through a dog clutch. 
     
     
       15. An electrically variable transmission comprising:
 an input member to receive power from an engine; 
 an output member; 
 first and second motor/generators; 
 first, second and third differential gear sets each having first, second and third members; 
 said input member being continuously or selectively connected with a member of said gear sets, and said output member being continuously connected with another member of said gear sets; 
 a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set; 
 a second interconnecting member continuously connecting said second member of said first gear set with said second member of said second gear set; 
 a third interconnecting member continuously connecting said first member of said third gear set to a stationary member or to said second or third member of said second gear set; 
 said first motor/generator being continuously or selectively connected with a member of said first or second gear set; 
 said second motor/generator being continuously connected with a member of said second or third gear set; 
 a first torque transfer device selectively connecting said input member or a member of said third gear set with a member of said first or second gear set; 
 a second torque transfer device selectively connecting said input member or a member of said third gear set with another member of said first or second gear set; 
 a third torque transfer device connected in parallel with said first motor/generator for braking rotation thereof; and 
 a fourth torque transfer device connected in parallel with said second motor/generator for braking rotation thereof; 
 wherein said first, second, third and fourth torque transfer devices are selectively engagable to provide an electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios. 
 
     
     
       16. The electrically variable transmission of  claim 15 , further comprising a fifth torque transfer device selectively connecting a member of said first, second or third gear set with a stationary member or said input member.